Apple thinning this year will be difficult in some areas of the state. Frost damage has eliminated kings on some varieties and, in more severe situations, has killed significant parts of the side bloom. There will be differences within orchards and even within trees.

Last year’s crop was a moderate crop for most growers. This means that this year’s bloom and fruit set should be strong. One new complicating factor is the warm winter we experienced. There have been reports around the world that when warm winters occur, fruit set is fair and thinning is easier. This year most varieties have an abundance of leaves present during the bloom. This should serve to strengthen the bloom.

Where bloom is not damaged by frost, aggressive thinning will be needed. Bloom density seems to be quite high for most varieties, due to the moderate crop last year. Plan to apply combinations of Sevin plus BA or Sevin plus NAA at the 10 mm stage. Where fruit set looks especially heavy, an across the board Sevin application at petal fall will help start the thinning process. Sevin is very effective at petal fall if weather conditions are favorable for application. Make sure bees are out before applying Sevin at petal fall. Use BA on the small fruited variety and Red Delicious and Fuji because those varieties are sensitive to NAA. Where king fruits are missing, it is going to be difficult-to-impossible to get a perfect thinning job. Be cautious and perhaps wait until 12 mm to make the first application. This way you will be better able to evaluate fruit set. At 12 mm to 15 mm you will still need combinations to achieve thinning; however, use only moderate rates. Where frost damage occurs, often the top half of the tree is probably undamaged and will need full thinning to achieve large quality fruit. Thin only the tops. As you drive up and down hills, in and out of frost pockets, gear up through the low areas and slow back down through the tops of hills to get a better thinning job.

All thinners work best when temperatures are warm, above 65 degrees, but we prefer to have temperatures after the application to be in the 80’s. If you are not getting warm temperatures, consider delaying until a warmer forecast of temperatures occurs. The temperature at the time of application is not important, the temperatures 2 to 3 days following the application are critical for effective thinning. This year, with the considerable frost damage, will make it more difficult to achieve perfect thinning. Where frost is not a factor aggressive thinning will most likely be needed.

There are four points that I would like to make concerning Apogee for the 2006 application season. First is timing, second is rate per acre, third is thinning relationships, fourth compatibility.

Timing. Apply Apogee when vegetative shoot growth is less than 3 inches. This is about a 7 to 10 day window commencing at the king bloom petal fall stage. Most years all varieties can be treated at this time. The second application should be applied two weeks later and the third application two weeks after the second. Sometimes a fourth application is needed, but that is optional based on crop load and tree vigor. Excessive rainfall and light crops will promote vegetative growth; therefore an additional fourth application may be needed.

Rate. Rate per acre is usually calculated on a tree row volume basis and adjusted to 2/3 of the label full rate. This 2/3 rate/acre is a season long rate per acre. For example, if your trees are 75% tree row volume then 24 ounces per acre is the seasonal rate (48 * .75 * 2/3). Best results occur when seasonal rate is split into three or four sprays. For example, 8 + 8 + 8. When fire blight is a severe risk, the first application at king bloom petal fall timing should be increased, perhaps as much as 150% of a split rate. For example, increased from 8 ounces per acre to 12 ounces per acre. Subsequent sprays, the second and third sprays could be reduced, so the seasonal application would be 12 + 6 + 6 = 24 ounces per season.

Thinning. Apogee tends to increase fruit set, therefore more aggressive thinning is needed. Increase your thinning by 10 or 15%.

Compatibility. Apogee is not compatible with calcium or boron in the tank. Also, we suggest that Apogee be applied after a thinner. If the two-week timing interval is also the ideal time to thin, make your thinning application first and then a couple days later follow with Apogee. Remember to include the label recommendations for AMS and surfactants.

In a summary; Apogee is an excellent tool to help control vegetative growth and especially suppress fire blight spread among shoots and within shoots. Follow these tips to get the most out of Apogee.

Even though the winter was quite mild, some sweet cherries in northwest Michigan are exhibiting significant winter dieback. Most of the affected trees show whole or partial limb death and often include death of last year's terminal growth. This winter injury is directly related to tree stress last season. Tree stress in 2005 was caused by a combination of severe drought, very heavy crop loads and hot weather. Ethephon applied under hot, dry conditions often resulted in midsummer leaf drop and gummosis. Generally, the ethephon induced injury was most evident in the portion of the canopy closest to the sprayer discharge. This combination of stress factors resulted in wood that could not survive even a relatively mild winter.

In trees, where terminal dieback is common, one concern is that this year's crop of fruit will all be produced on spurs. Cherries produced on spurs depend, in part, on leaves from last year’s terminal growth to provide adequate carbohydrates to size the fruit. If fruit set is heavy, death of terminals will likely result in smaller fruit because the cherries just do not have the resources from those important terminal leaves.

Because of the advanced season, there are few management strategies that could be used at this stage. However, growers should try to minimize stress factors in 2006 in all orchards exhibiting symptoms of excessive dieback this spring: 1) Maintain a good overall nutrition program and apply N at higher than normal rates to help stimulate strong growth this season. 2) Maintain a spray program that will keep leaves on trees into the fall, and 3) Avoid further ethephon damage this season.

Pest management in frost-damaged vineyards
Rufus Isaacs, Entomology
Annemiek Schilder, Plant Pathology

Introduction
The damaging weather conditions in southern Michigan vineyards this spring has created a need for growers to consider an adjusted insect and disease control program for frost-damaged vineyards. The comments below are intended to help growers reduce pest management costs while maintaining a program to address critical needs for vine protection.

Even though the current yield loss estimates are high, it should be kept in mind that the actual remaining yield potential will not become apparent until after the secondary buds have pushed and clusters have appeared. These guidelines are therefore dependent on managers making decisions about the level of crop remaining. If shoots were heavily damaged by frost but there are enough clusters to harvest some fruit, the focus should be on minimizing the cost of pest management inputs while maintaining quality and yield of the remaining fruit. In a year with a small crop load, the foliage will easily be able to produce sufficient sugars for maturation of the fruit as well as buds and wood for next year. Therefore, the need to protect the foliage from damage by insects and diseases is much lower. In fact, increased canopy size can become a problem due to increased shading, which leads to reduced formation of fruit buds.

Scouting
If a crop is to be harvested from a vineyard, regular scouting can help avoid any more surprises. At the very least, checking vineyards post bloom, in mid-July, and in early August can provide the minimum of information regarding development of key insect pests and diseases. If the cost of hiring a scout seems too much, try negotiating a lower price before canceling this service. Alternatively, walking the rows once a week can help you keep up to date on vine and pest development and will cut down the cost of this service. This might take about 1 hour per week. It may not seem worth it to spend any time in some badly affected vineyards, but consider this an investment in the long-term future of the vineyard. A form to help with keeping records of your scouting is available at www.isaacslab.ent.msu.edu/grapescout/scout.pdf

Insect management
Foliage pests. Decisions for insect control will depend on the expected yield from each vineyard. If it is expected to be close to normal, a typical insect control program should be maintained to guarantee the expected yield and quality. If a lower than normal crop will be harvested, juice grapevines can tolerate leaf damage and still ripen the reduced crop. Because of this, it will be much less important to control Japanese beetle, rosechafers, and leafhoppers than normal. If no post-bloom insecticide application is made, leafhopper infestation can be checked in mid-July to determine the need for controlling this pest. The threshold for juice grapes with a full crop at this time of the season is ten percent of leaves infested. Although thresholds have not been developed for situations with a reduced crop, they are likely to be much higher as the crop load decreases. As mentioned above, the need for foliage protection will be low this year, so only those vineyards where a high leafhopper infestation is discovered will need treatment. If no crop will be harvested this year, the cost of protecting vines from leafhoppers and beetles is unlikely to be economical in juice grape vineyards. Hybrid and Vinifera vines are less tolerant of insect feeding than juice grape varieties. If bearing vineyards of these varieties are infested by foliage pests, leaf protection remains important for achieving fruit ripening and vine maturation. Regular scouting can be used to determine the need for, and timing of, interventions to control foliage pests. See above for a link to a scouting form.

Cluster pests. A program for control of grape berry moth, which is the main pest of grape clusters, should remain a priority if any grapes are to be harvested. This will help minimize crop loss this year, and will reduce the risk of high infestations next year. Application of a post-bloom insecticide to vineyards that have a history of high GBM infestation is warranted if the vineyard will be harvested. Sampling again in the first half of July (same time as leafhopper samples above) can be used to determine whether the cost of further insecticide applications is warranted. It is worth keeping the sprayer on hand after veraison, in case populations of grape berry moth continue to develop close to harvest. If this occurs and berries are at risk from infestation, a well-timed effective insecticide may be warranted prior to harvest to minimize risk of infestation in harvested berries. If grape berry moth infestation is restricted to wooded borders, cost savings may be achieved in some vineyards by applying border sprays to the outer ten rows. Cluster sampling in mid-July can help identify vineyards where this strategy would be worthwhile.

Disease management
Foliar diseases. The main foliar diseases that are important in Michigan juice grapes are powdery mildew in Concord and downy mildew in Niagara grapes. If no fruit will be harvested, foliar diseases are the only diseases that need to be considered. As with insects, vines with a small crop load will be able to tolerate more foliar disease. In Concord grapes, control of powdery mildew may not be needed at all, unless there a concern about excess inoculum production for next year. In that case, one or two mid- to late-season applications of a sterol inhibitor fungicide will probably be sufficient to reduce further infections and production of cleistothecia. Sulfur (for non-sulfur-sensitive varieties) and JMS Stylet Oil are lower-cost alternatives for control of powdery mildew. JMS Stylet Oil has the added benefit of killing powdery mildew colonies on contact. Downy mildew can be more harmful than powdery mildew, as it can lead to severe defoliation and reduced winter hardiness of the vine. Even though vines with a small crop load can withstand more downy mildew than heavily cropped vines, it should not be allowed to go completely out of control. This is also important from the standpoint of overwintering inoculum for next year.

I would recommend scouting of vineyards in mid-July. If downy mildew lesions are observed, an application of Ridomil can be made to eradicate the disease and stop further spread. Scout again 2 to 3 weeks later to check if further control is needed. Less costly alternatives are copper products (for non-copper sensitive varieties), phosphorous acid fungicides (e.g., Phostrol, ProPhyt) and Ziram. Coppers and Ziram are strictly protectants, whereas phosphorous acid products have strong curative activity and will stop disease development for up to 6 days after an infection has started (this is when the lesions are just starting to show). They don’t have much residual activity, however, so they may need to be tank-mixed with Ziram to get longer protection. The phosphorous acid products also have good activity against Phomopsis and moderate activity against black rot. For growers that have already applied dormant sprays, you can expect a reduction in powdery mildew if you applied sulfur, and a reduction in downy mildew if you applied a copper fungicide. In small plot trials in Michigan, reductions of 40-60% were observed compared to untreated plots.

Fruit rot diseases. Black rot and Phomopsis are the main cluster diseases to be considered if there is sufficient fruit to harvest, especially if there is a lot of overwintering inoculum (fungi are not affected by a freeze). Luckily, most vineyards experienced low disease pressure in 2005, so fungicide applications may not be as critical this year. Black rot control should be focused around bloom, with the first and second post-bloom sprays being most important. There is generally no need to protect the fruit beyond the second postbloom spray, because the berries become naturally resistant to infection about 4 to 5 weeks after bloom. Elite + Ziram or even Elite alone will suffice. Other options are strobilurins, such as Abound. Phomopsis control becomes important as soon as the flower clusters become visible, which will happen a little bit later this year as we will rely more on the secondary buds. Phomopsis spores will be released during most rain events from budbreak until about bunch closing. A peak in spore production usually occurs around the first and second week in May, which may be a good time to protect shoots from infection. The amount of overwintering inoculum can be estimated from the number of lesions on current-season shoots and leaves. During dry spells, fewer sprays will be necessary. In many years, we have not seen a benefit from sprays beyond the first post-bloom spray. Mancozeb is a cost-effective material for use against Phomopsis prior to bloom, and Ziram can be used after bloom. For growers that have already applied dormant sprays, you can expect a substantial reduction in Phomopsis through the season. The only other sprays that may be needed are an Abound spray at bloom or first postbloom, and if a wet spring, a mancozeb pre-bloom. Pristine may be a cost-effective option in Niagara, but the label claims a risk of phytotoxicity on Labrusca-type grapes. Botrytis bunch rot is primarily a concern in tight-clustered Vinifera and hybrid grapes. Protection may be needed if conditions are wet in the period between bunch closure and harvest, with veraison being a critical time. A bloom spray usually is not cost-effective. One or two applications of a fungicide like Vangard are most effective for control of this disease. Scala may be a lower-cost alternative for Botrytis control.

Coverage
Because cluster protection is the main focus of a reduced insect control program, it is best to target sprays to the fruiting zone to maximize the effectiveness of sprays. For effective grape berry moth control, spray deposits must reach the whole cluster. This becomes more challenging as the vine canopy grows and so as the season progresses, spray volume should be increased and every row should be treated. Field trials with an airblast sprayer have shown that a spray volume of 50 gpa achieved substantially better disease control, particularly with protectant fungicides, than a spray volume of 20 gpa. The same result was found for control of grape berry moth – increasing gallonage to 50 gallons provided better control than 20 gallons. Although this will take more time, getting the maximum effect out of every spray is particularly important when yield is expected to be low.

Product selection
Under times of financial challenge, the temptation may be to choose the least expensive option to achieve control. This may seem the best choice, but it is good to keep in mind other factors. For example, is the product effective under the current and predicted weather conditions; how long does it last; and how well will it control the target pest or disease? In the long run, it may be more cost effective to use a slightly more expensive product that lasts longer than the cheapest option. Depending on existing pest and disease pressure, a lower labeled rate may be used, though.

Timing
When cutting back on sprays, make every one count. Making sure that applications are made at the optimal stage for control of your target pest is another way to help cut costs. It may take a little more time to check vineyards closely every few days, but doing this can be a cost-effective way to improve the impact of your spray program. By doing this, you may also find that pests and/or diseases are not as bad as expected, and the cost of an application can be saved.

Insect and disease control approaches in frost-damaged Concord or Niagara vineyards.

Bloom is a critical time for blueberry producers. When bees are numerous and weather is warm and calm, 80 to 100 percent of flowers may set fruit. Pollinated flowers drop their corollas (petals) while they are still white and fruit begin growing rapidly. Berry set and growth is dependent on the production of gibberellin and perhaps other growth promoters in the ovary tissues and viable seeds. Berries appear to require a minimum number of seeds to attain full size. If pollination is adequate, most all berries contain 20 to 60 seeds, well over this minimum seed number. If pollination is limited, final berry size may be proportional to the number of seeds.

Cold and windy weather during bloom can prevent bees from transferring pollen to flowers or prevent the transferred pollen from fertilizing the ovaries of the flowers. Under these conditions, flowers may set no fruit while others set fruit that contain too few seeds to grow to full size. Under these conditions, bushes may benefit from supplemental gibberellin (GA) sprays. Several GA products (ProGibb, GibGro) are labeled for highbush blueberries. GA typically results in greater retention of some parthenocarpic (seedless) fruit that would have dropped and also increases the size of berries without a full complement of seeds. GA can be applied in a single spray during bloom (80 gram active ingredient per acre) or two 40 g sprays, one during bloom and the second 10 to 14 days later. Higher spray volumes (40 to 100 gallons per acre) may improve coverage and effects. Slow-drying conditions also increase absorption. Also make sure your spray water pH is not above 7.5. Since the response to GA can be inconsistent and subtle, leave non-sprayed rows so you can later judge whether the treatment was helpful.

Since the cost of 80 g of GA is over $100, it is important to know when pollination is limiting and GA may be helpful. If weather has been reasonable good for bee activity and the white corollas fall easily from the bushes, pollination is probably adequate. Keep in mind that blueberries can bloom over a long time, and often only a few days of good conditions is enough to provide adequate pollination and fruit set. Consistently cold, rainy and/or windy weather through bloom causes pollination problems. If the corollas stay on the bushes and turn red-purple before eventually dropping, pollination may have been inadequate. The corollas of pollinated flowers drop readily while still white. Varieties with fruit set problems (Jersey, Coville, Earliblue, Berkeley, Blueray) are most likely to benefit from GA. Jersey, for example, is relatively unattractive to honeybees, and berry numbers and size are often limited by inadequate pollination.

Rabiteye blueberry growers in the Southwest have found that GA may also help overcome slight freeze damage to flowers. The rabbiteye recommendation is to apply 24-32 oz ProGibb just after a damaging frost event and repeat the application in 10-18 days. There is some observational evidence that this can work in Michigan highbush as well. If you use GA after a frost event, please leave untreated areas as checks. Contact me by phone (517-355-5191) or email ( hansone@msu.edu), as I would like to assess the effect.

Since 1996, blueberry growers with fields located alongside major highways in west Michigan observed that plants located in front of the roads were suffering extensive dieback and flower bud mortality. The damage followed a gradient with the heavier damage in plants within the first 30 meters from the road (in some cases up to 100% flower bud mortality) and slight damage or no damage at all 100 meters away from the road at the back of the field. With the aid of MSU Extension, growers tried to find the reason behind the damage and the only explanation, apart from natural winter damage, was the possible effect of deicing road salt applied to major highways during the winter. With funding from Project GREEEN, MSU Extension, Ottawa County Board of Commissioners, and MBG-Marketing (the Michigan Blueberry Growers association), studies were conducted between 2001 and 2004 to determine the cause of this injury. Results showed that injury levels were proportional to salt residues deposited on twigs and proximity to roads. The injury symptoms were duplicated by treating plants with salt sprays. It was concluded that road salt blown into fields was the cause of the injury. It has been estimated that e very year, blueberry growers affected by road salt suffer losses in plants and revenues amounting more that $600,000 (Figure 1).

In response to economic and environmental concerns, the Ottawa County Road Commission developed an Integrated Road Salt Management Program (IRSMP) to reduce damage while maintaining safe roads. The IRSMP was implemented in the winter 2004-05. The IRSMP attempts to reduce road salt usage and limit blueberry damage in designated “Environmentally Sensitive Areas” while maintaining safe road conditions.

During the winter 2004-05, we initiated an evaluation of the implementation of the Ottawa County Road Commission IRSMPat five blueberry fields located within those “Environmentally Sensitive Areas” designated by the Road Commission. Monitoring sites were adjacent to divided highways, undivided highways, and secondary streets. As a control we used a blueberry field adjacent to gravel, unsalted road. Six sampling sites were defined in each field; three close to the adjacent road (usually 30-40 meters), and three 100-110 meters from the road. Data collected at each site was:

1) Twigs and bud mortality. Flower buds were examined with a dissection microscope and percentage of damage estimated.

2) Sub-surface water and soil sampling. Water was collected from the blueberry’s root zone at a depth of 1 meters using PVC water access tubes (Figure 2). Simultaneously, soil samples were collected at each field location to a depth of 30 cm (approximate blueberry rooting depth). Water and soil sampling was conducted from November to April and pH, and extractable sodium and chloride was estimated.

3) Salt levels in area irrigation ponds estimated. At each site, two samples of 250 ml each were taken from irrigation ponds in the proximity of the monitored farms (ponds were located greater than 30, less than 50, 100, and less than 400 meters from any salted road). Water samples from irrigation ponds and from water access tubes were collected on the same day.

Results showed that, in November 2005, even before any salt was applied, sodium and chloride concentrations in water samples taken from the blueberry root zone at the sampling site located in front of US 31 (a major highway) were already 20 times higher than those from a control field in Buchanan Street – a non-salted road. At the field located along side the major highway, US 31, sodium and chloride concentrations 30 meters away from the road were 246 and 506 ppm versus 11 and 21 ppm in the control site at Buchanan Street.

In mid-January 2006, after the first winter storms, those concentrations decreased but remained very high; 102 and 149 ppm for Sodium and Chloride, respectively. No significant change in salt concentration occurred at the control site (Sodium= 6, Chloride = 10 ppm). Water samples taken from the root zone at the site located in front of Highway M-45, showed that sodium and chloride concentrations previous to the winter storms were on average 22 and 38 ppm, respectively. However, those concentrations decreased to 8 and 16 ppm in mid-January 2006, an approximately 50% reduction after the winter storms. Sodium and chloride concentrations in secondary roads, 120 th Ave and Port Sheldon, were much lower than in front of US 31. In mid-November 2005, sodium and chloride were on average 19 and 33 ppm while in mid-January 2006 they were 12 and 44, respectively. This showed that at least in the secondary roads sodium chloride contraptions were almost unchanged.

In mid-November 2005, water from irrigation ponds located less than 50 meters from a salted road showed higher sodium and chloride concentrations (23 and 50 ppm) than those located 100 meters away or more (9 and 37 ppm). However, in mid-January 2006 sodium and chloride concentration at the same ponds was 16 and 44 ppm and 9 and 31 ppm, respectively.

Regarding flower bud damage, in mid-November 2005 before the winter storms, bud and shoot damage 30 meters away from the road was 20% at the blueberry field located in front of US 31 but 0% at the field located in Buchanan Street, a non-salted road. After the storms, mid-January 2006, damage at the same sites increased substantially: 82% at the field located alongside US 31 and 20% at the control site located at Buchanan Street. Damage at the secondary roads was similar to that observed at control site at Buchanan Street.

In summary, our preliminary evaluation of the implementation of the Ottawa County Road Commission Road Salt Management Program indicates that there seems to be a wash off of salt at all sampling sites right after the melting of snow. That causes a significant decrease of sodium and chloride concentrations in all affected fields. On the other hand, there seems to be a reduction on damage to blueberry fields located in front of secondary roads. But it remains high at the site located alongside US 31.

Although we observed some substantial differences between major highways and secondary roads with respect to sodium and chloride concentrations and flower bud mortality, one year of evaluation is not enough to judge the success of the Ottawa County Road Commission IRSMP. However, o ur preliminary evaluation indicates that reducing the application of salt for only one season may not be enough to reverse the environmental degradation cause by more than 15 years of use of deicing salt.

Insecticide regulatory correction
John Wise and Larry Gut
Entomology

Correction on Proclaim label description
We published a short article last week describing the new Proclaim 5SG pome fruit label. A correction to that description is that Proclaim belongs to the Avermectin class of insecticides, not the Naturalyte class as was reported.

Regional reports
1 -- Southwest
Mark Longstroth
Bill Shane
Al Gaus

Apricots in the shuck were extensively damaged. All but the best sites have little fruit left.

Peaches are at petal fall. Damage was severe in some sites. Bloom was very heavy so there is still a marketable crop in many orchards. We set biofix Oriental fruit moth as April 16 with a GDD45 of 180 at SWMREC. Chemical controls are focused on egg hatch about 150 to 170 GDD45 after biofix. We are about 140 GDD past biofix and treatment should be applied soon. Sunday’s rain was a marginal brown rot infection because of the cool temperature and was also probably too cool for bacterial spot.

Sweet cherries are in the shuck and were hurt hard by the freeze. Growers with good sites report they still have a crop but lower orchards show extensive damage. Cherry leaves are unfolding so growers need to protect against cherry leaf spot. Sunday’s rain was a marginal cherry leaf spot infection in some locations.

Tart cherries: Montmorency cherries are at petal fall and were in full bloom during the freeze. The heavy bloom apparently protected most of the flowers because there was generally only light damage. Damage estimates are about 20% loss. The most common symptom was browning of the style where it joins the pistil. These flowers are unlikely to set fruit. By Monday dead pistils were easy to find and identify. Leaves have unfolded and growers need to protect against cherry leaf spot . Sunday’s rain was a marginal cherry leaf spot infection.

In plums, Oriental plums were in the shuck and hit hard by the freeze. European plums were at full bloom and suffered less damage. Sunday’s rain was certainly a black knot infection. Plums are now at petal fall and Sunday’s rain was a marginal brown rot infection.

Apples are blooming. Many open flowers were killed by Wednesday’s frost. In many cases the king bloom and some of the side bloom are dead. Early varieties in lower sites were hardest hit. Later varieties were only lightly affected. Sunday’s rain was an apple scab infection. Symptoms should appear about May 14. Scab symptoms from earlier rains should be appearing but none were found Monday. Warm, wet conditions this week means that growers need to maintain scab protection. While the weather is warming there is no danger of a fire blight infection this week, as the warm weather will not last long enough to allow bacteria populations to build. So far the dry conditions have kept fire blight cankers from doing much oozing, but I expect a lot of ooze in orchards with cankers this week. An extended warm period later in bloom could easily result in fire blight blossom infection towards the end of bloom. Growers can monitor wetting periods for scab and fire blight infections at the Enviro-weather site. We are now trapping redbanded leafroller and Oriental fruit moth. No codling moths were trapped this week. We expect the flight to begin with warm dry weather. This week will be too cool for thinning. The wet, cool weather, and the frost should make thinning easier . Growers should be prepared to thin apples next week.

Pears are at petal fall and were not severely affected by the frost. Growers need to protect against pear scab.

Grapes were the hardest hit by the freeze suffering severe damage. Juice grapes were more advanced than wine grapes and have more obvious damage. Over large areas, almost all the growing shoots were killed and growers report that many secondary buds had pushed and were killed also. This freeze was similar to one in April 2002 that killed most of the shoots. In 2002, several weeks passed before secondary bud growth was evident. Initial estimates of primary bud mortality are about 25% in good sites up to 100% in many areas. Secondary bud mortality is also high is many areas. The potential juice grape crop has been reduced by at least 50% and probably more. Wine grapes suffered much less damage. A more accurate estimate can be made in about a month when the flower clusters in new replacement shoots are apparent. Growers with large areas of good growth should continue their disease control programs. Growers with only scattered live shoots will want to wait until closer to bloom to decide in they should continue to protect the crop. This decision needs to be made in time to allow the prebloom spray, which is very important.

Strawberries are beginning to bloom. Growers protected against the freeze with sprinklers, but in some cases the flowers still froze. This could be due to turning on the sprinkler system too late when temperatures are already near freezing or a simple failure of the system to protect down below the low 20s. Growers should consider fungicide applications at bloom under these wet conditions.

Leaves are emerging on blackberry and summer raspberry canes. Fall raspberry shoots are 4 to 6 inches tall. The freeze did burn some new shoots on the ground and on the canes but the plants should recover with a good crop.

Cranberry buds are beginning to swell and some areas of the beds are greening up.

The next Monday Fruit Update meeting will be, Monday, May 8, at the Fruit Acres Farm in Berrien County, at 5:00 PM .

2 -- Southeast
Bob Tritten

The first frost/freeze event started on Tuesday night April 25 and concluded the next morning. One thing that was very unusual about this event is that it turned very cold on Tuesday night and temperatures remained cold and steady throughout the rest of the night and into early next morning. I have seen hourly weather data that indicates that temperatures on that night hit 25 to 27 degrees, and these temperatures were reached around 10:00 PM to 11:00 PM in the evening and stayed cold throughout the entire evening through 8:00 AM the next morning. While I have seen cold temperatures this low several times over the years, the length of the cold was extreme and may be one for the record books. I have talked to several strawberry growers who started irrigating strawberries to make ice around 9:30 PM to 10:00 PM at night and continue to irrigate all the way through 8:00 AM to 9:00 AM the next morning.

The next night, April 26, saw cold temperatures, but not nearly as cold as the night before. Many people are talking about temperatures in the range of 31 to 35 degrees that night. The following night, April 27, was another cold event, however much shorter in duration than the one on Tuesday night/Wednesday morning. I have heard of temperatures as low as 26 degrees on that night, most places reaching a low of 29 degrees at around 5:00 AM in the morning. The next night also brought more cold to some areas, in the range of 30 to 34 degrees.

What was strange about these events was that orchards located just a few miles apart, damage ranged from no injury to 90% bud kill for the same crop. Overall I would say apples had a fair amount of damage, in the range of 30 to 50 percent. Pears appear to have had moderate to severe damage. Peaches seem to have come through just fine. Sweet cherries have a variety of damage rating. Tart cherries seem to be OK. Strawberries were severely injured at several farms. Blueberries appear to be OK, and grapes had some frost/freeze injury. More details follow in each section of this report and in next Tuesday’s report.

Our season is now running about 8 to 10 days ahead of normal for most reporting stations. Cooler temperatures the last few days have slowed our growth considerably. The soil conditions remain very dry. Many growers have now begun to irrigate newly planted tree and small fruits. I am hopeful for some nice rain events this week; however, the prediction is not calling for widespread heavy rainfall.

The insect story of this week is heavy flight of Oriental fruit moth that occurred as of Saturday, Sunday and yesterday. I am seeing trap catches in the range of 40 to 50 per trap. I biofixed my traps on April 29. There is a no codling moth flight. Most people set codling moth traps last week. Obliquebanded leafroller trap catches are generally down. Spotted tentiform leafminer trap catches are also down as the end of the first generation adult flight now approaches. European red mite egg hatch occurred mid- to late last week. European red mite numbers are fairly low with the exception of a few blocks that had a heavy infestation last year and a good egg survival rate over the winter. Apple rust mites are now being seen feeding in apple leaves, however their numbers are fairly low at this time. There are a variety of beneficial insects now being seen. These include good numbers of ladybird beetles, Amblyseius fallacis, Stethorus punctum and even a few early lacewing adults.

Most growers have not had an apple scab infection over the last week. There were some rain events over the weekend, however for the most part things dried off quickly enough that we did not have an infection period. With the general lack of rainfall at our apple scab spore trapping sites, there is little to no spore discharge. I was expecting to begin to see apple scab lesions show up mid- to late last week from infections earlier in the spring, however none have been seen yet. Growers need to be on the alert for possible fire blight infection now that open blossom is here and the possibility of rain and warm temperatures exist for the next day or so. Fire blight is high on my radar screen.

Pears are mostly at full bloom. I would estimate that we have had about 30% to 50% bud kill on pears from the frost/freeze event. Pear psylla adult flight has continued over the last week, and I am now seeing more blocks where egg laying has begun.

Peaches are at full bloom for most varieties to early petal fall. It appears that there was little to no damage to peaches as a result of the cold events of last week. Again Oriental fruit moth trap catches have jumped dramatically in trapping of both apple and peach blocks. See the Oriental fruit moth reference in the apple section for more details.

Sweet cherries continue in full bloom to early petal fall. There is a wide spread of frost /freeze damage on sweet cherries from nearly 100% survival to close to 80% to 90% bud kill. I need to wait for a bit longer to see the full extent of the frost/freeze damage to sweet cherries. Brown rot spraying has been made on many blocks of sweet cherries late last week. Leaf spot sprays are starting this week.

Tart cherries are in full bloom. There appears to have been no damage.

Plums are at full bloom. Blackrot sprays are being applied fairly quickly on plums. There appears to be little to no damage.

Raspberries continue to push along new growth. There were several summer red raspberry patches that I had seen cold damage to the newest or most tender foliage and growing tip. While this will slow up the growth a bit on summer red raspberries, they will rebound quite nicely and grow out of this leaf and bud kill fairly quickly. Fall red raspberries were burned back to the ground due to the frost/freeze event. Again, new canes will emerge fairly quickly and most will most likely not have a long lasting impact on fall red raspberries.

Blueberries are at early to mid pink bud. While that is a bit more difficult to assess frost/freeze damage, it appears that there was little to no damage. There are no other pest problems to report. The dry weather thus far this spring has meant that mummy berry mushroom formation has been much less than in typical years.

Grapes were hurt some in last week’s frost/freeze event, however I think that buds were still tight enough that there are still a good crop of grapes. Again time will tell. Look for more details in next week’s report.

3 -- Grand Rapids Area
Amy Irish-Brown
Carols Garcia-Salazar

Temperatures on the mornings of April 25 and 26 were quite cool – some areas reported low around 24 or 25 in the coldest spots around the Ridge. It was colder yet in the Fremont area. So far, flower bud damage on tree fruits is not that significant – perhaps about 10% damage overall.

The only rain since the last Fruit CAT Alert was Sunday into Monday (April 30-May 1) and it was pretty light. Rainfall was quite variable with measurable rain late Sunday afternoon at the Sparta and Fremont weather stations; and in Belding and at CHES, no rainfall recorded until early Monday morning. This infection period has come to an end for all areas because we’ve had 8 hours of drying time. More rain is predicted for today and Wednesday, which will be a separate infection period if we get enough hours of wetting. Spore numbers were light from the last rain. According to the model used to determine spore maturity, we are just about at 75% mature spores, so the potential is there for some really high spore releases over the next week or so – this is not the time to stretch out cover sprays – we’re right in the middle of the highest pressure from apple scab.

Fire blight was not a concern with open bloom and the rain Sunday and Monday. Temperatures were lower than needed to build bacteria populations. Any rain we get on open bloom from now until petalfall will be more of a concern over the next few days – the forecast is calling for temperatures closer to 70 degrees and rain and there will be much more bloom open. Keep in mind that for those blocks with known Streptomycin resistance, you need to have Mycoshield on ahead of a wetting event for blossom blight and any bloom that was not open at the time of application will not be protected when it does open, unless you reapply. The same is true with Streptomycin on unopened bloom, but you can apply streptomycin within 24 hours of the beginning of a wetting event, rather than ahead of it like Mycoshield.

In apple, green fruitworm larvae are being found, as is overwintering obliquebanded leafroller larvae. Spotted tentiform leafminer should have started flying last week with some warmer nighttime temperatures. Climbing cutworm damage in apple buds has been reported. European red mite egg hatch is being seen in some areas. You should start trapping Oriental fruit moth at any time.

Many growers were applying pink sprays over the last several days – there is still time to get them on in later blooming varieties, but be sure you are aware of neighboring blocks that may have bees set out already.

With bloom coming on, apple growers will need to think about adding a mildewcide in the tank for powdery mildew in the next week or so for those varieties susceptible to it.

Brown rot sprays in sweet cherries and peaches in bloom should be applied – these rainy days during bloom will promote brown rot at harvest time.

4 -- West Central
Mira Danilovich

Weather
This is one time when it would have been better if the meteorologists missed the mark, but, they were right on target! The predicted frost hit the area on Tuesday night (April 25) and left some serious damage in the area particularly in Manistee/Bear Lake area where the temperature dropped well below freezing and stayed there for 10 hours. Our automated weather stations reported overnight temperatures for Manistee/Bear Lake area from 25.6 to 29.4°F. Most of the orchards in the area are at the lower elevation meaning that the temperatures at those locations were several degrees lower leading to very significant bud damage and in many cases crop loss. Hart and Ludington stations registered two hours of temperatures around 29°F. Fortunately, there was no “repeat performance” on Wednesday and Thursday night, though we still experienced temperatures near the freezing mark. In Hart and Ludington overall damage was minor though there are certain blocks in low-laying areas that have suffered much more significant bud mortality going from 50 up to 90%. Due to the configuration of the terrain within the same block, some localized low spots on the otherwise very good “cherry-site” had cherry bud mortality in excess of 90%. Apples have suffered king bloom losses and in some instances the side blooms were gone as well. Overall, Oceana and Mason county orchards are still in good shape. Manistee County did not fare as well.

GDD totals from March 1 to April 30

The weather forecast is predicting rain for much of the coming week creating very favorable conditions for apple scab. Currently, we are having an ongoing scab infection throughout the area. The severity index of infection may change with the rewetting event(s). Forecast is calling for scattered rain late this evening and through the night and into tomorrow. This has the makings of a serious infection potential.

Though we did have slight cool-down in temperatures, the vegetation does not seem to have slowed down. There is a lot of new green tissue out that must be protected. Following the principals of good pesticide resistance management practices, Vangard in combination with some of the protectants (Captan or EBDC fungicide) could be an option at this time. This is pre-bloom material that works better under cooler conditions and, given the current weather conditions, it could make a good fit. Vangard is protectant with some after-infection capability if applied at full label-recommended rate up to 48 hours post infection. Other possibilities would be strobilurins ( Flint, Sovran, Pristine), SI’s (Nova, Rubigan). Any of these materials should be applied in combination with protectan fungicides to maximize disease control and delay fungicide resistance development.

Moderate cherry leaf spot infection is in progress for the Hart area and low infections in progress for Ludington and Manistee/Bear Lake areas. Bravo is a very good fit at this time since it cannot be used after shuck split. It is rated excellent for cherry leaf spot and will provide good protection for blossom brown rot. Other options include but not limited to include Indar (excellent for leaf spot and blossom brown rot) and Pristine (excellent for leaf spot and powdery mildew).

Plums are subject to leaf spot infections and require protection at this time. Spray options are Rovral, Elevate, Bravo, Vangard, Orbit, Pristine, Topsin-M and Captan.

This is very favorable if not the optimum time for spore discharge and infections of black know. It is essential that the blocks are cleaned form the old cankers and sprayed with fungicides like Captan, Bravo (until shuck split) and/or Topsin-M that will help control this disease and keep “in check” further spread. Now is the opportune time to check the surrounding areas for the presence of any wild Prunus sp. that might have been the source of initial infection and remove them.

All stonefruit is in various stages of blooming and is very susceptible to brown rot/blossom blight infections. Any mummies missed during pruning and left hanging on the trees will become main inoculum source. Some of the available materials that will aid in disease control are Elite, Indar, Nova, Orbit, Rovral, Bravo, Topsin-M, Pristine, Vangard (not to be used on sweet cherries), Captan and sulfur.

5 -- Northwest
Nikki Rothwell
Jim Nugent
Duke Elsner

Cutworms are particularly active this year in newly planted orchards and grapes. Rosy apple aphids are present at low levels in apples. Spotted tentiform leaf miner is about at first adult peak. Second instar green fruitworm and obliquebanded leaf rollers are evident at this time

A wetting event beginning on April 30 in Benzie County resulted in a low level apple scab and cherry leaf spot infection period. Benzonia reported a grape leaf black rot infection. The rest of the region remained dry for the week.

Frost that damaged sweet cherry blossoms on April 28 is not expected to lead to significant bacterial canker infection, due to dry conditions before and after the event.

Weather news
Jeff Andresen

An upper air cut-off low feature will make its way slowly across the United States/Canadian border during the next several days, bringing several chances for precipitation across the Great Lakes region before a cool, Canadian-origin air mass moves in for the weekend. Rainfall (and an extended wetting event) will be a good bet across most of the state Tuesday into Tuesday evening (May 2 and May 4) with the formation of fog overnight into early Wednesday. A weak cool front will pass across the state late Wednesday, bringing another chance for showers, although areal coverage and amounts are expected to remain on the light side. Dry weather is expected statewide Thursday before another cool front moves through the state on Friday into Saturday, bringing yet another chance for showers. Rainfall totals during the next five days are expected to range from the 0.10- to 0.25-inch category in northern sections of the state to the 0.25- to 0.50-inch category in the south. Temperatures will slowly fall from highs in the 70s and lows in the 50s across most of the state Wednesday to highs in the 50s and lows in the 30s this coming weekend. Should clear, calm conditions develop Saturday or Sunday morning, frost and freezing temperatures will be a possibility once again.

Latest medium‑range forecast guidance suggests the gradual formation of an upper air troughing feature across the western United States with a broad ridge across the east. This type of pattern would likely bring a return of warmer and stormier than normal weather to Midwest (similar to the pattern of late March and early April).

The NOAA 6-10 day outlook (covering May 7-11) calls for below normal temperatures and above normal precipitation totals statewide while the outlook for the 8-14 day period (covering May 9-15) calls for warmer and wetter than normal conditions over Michigan and the entire region. The temperature forecast in the 6-10 day time frame is somewhat unexpected given the forecast change in upper air flow across North America. My personal guess is that while cooler than normal temperatures are likely during the upcoming weekend into early next week, warmer than normal weather will develop by the middle to latter part of next week.